1. Field of the Invention
The present invention is directed to an electropneumatic valve and more particularly, to an electropneumatic valve having a nonmagnetic unitary tappet with an integral valve disk.
2. Description of the Related Art
A pressure regulating valve disclosed at page 7.026 of a product catalog from Mannesmann Rexroth Pneumatik GmbH titled "Knowhow in Pneumatik" (Order No. 10/93) is constructed as a 3/3-way directional control seat valve having a proportional magnet drive. The valve part of this electropneumatic valve substantially comprises a valve body including connections for a compressed medium, electric signal lines, and a power supply. In the interior of the valve body, a valve part tappet with a valve disk interacts with a valve seat to ensure operation of the valve.
A proportional magnet is fastened to the valve part and comprises an electric coil and an armature having a tappet connected thereto--the armature and tappet being longitudinally movable and guidable within the coil. The armature is held in an initial position by a spring. The armature tappet transmits the force generated by the electric coil to the valve part via the valve part tappet. To actuate the valve part, the armature tappet impacts on the valve part tappet, this valve tappet likewise being guided along its movement direction.
The separate tappets are normally arranged in contactingly abutting alignment with one another. This contacting relationship between the tappets is necessary to prevent the armature tappet and the valve part tappet from striking one another abruptly when the valve device is switched on. Contact between the tappets is maintained by means of an additional spring inside the valve part that presses the valve part tappet against the armature tappet. The force generated by the coil for actuating the valve must accordingly overcome the force of the spring in the proportional magnet as well as the force of the spring in the valve body.
This disadvantageously effects and impairs the efficiency of the proportional magnet. The required spring force at the valve tappet reduces the available tappet force of the proportional magnet unit and accordingly also reduces the switching dynamics of the pressure regulating valve.